In https://reviews.llvm.org/D147812 I introduced the class
`BalancedPartitioning` and it seemed to trigger a warning in flang
```
C:\Users\buildbot-worker\minipc-ryzen-win\flang-x86_64-windows\llvm-project\llvm\include\llvm/Support/BalancedPartitioning.h(89): warning C4305: 'initializing': truncation from 'double' to 'float'
```
For good measure, I converted all double literals to floats. This should
be a NFC.
In [0] we described an algorithm called //BalancedPartitioning// (bp) to consume function traces [1] and compute a function order that reduces the number of page faults during startup.
This patch adds the `order` command to the `llvm-profdata` tool which uses bp to output a function order that can be passed to the linker via `--symbol-ordering-file=`.
Special thanks to Sergey Pupyrev and Julian Mestre for designing this balanced partitioning algorithm.
[0] https://discourse.llvm.org/t/rfc-temporal-profiling-extension-for-irpgo/68068
[1] https://reviews.llvm.org/D147287
Reviewed By: spupyrev
Differential Revision: https://reviews.llvm.org/D147812
